Confused about Murdoch Foyle (Series 1)

Could someone explain to me the time line of Murdoch? The first episode shows PF (Phryne Fisher meeting with MF in jail. He's been there several years and not likely to leave. But then in following episodes, he's supposed to have killed Marigold. Then he starts stalking Jane in the last few episodes. Has MF escaped from prison? Did I miss something?

As an aside, Jane, who is supposed to be very intelligent, is singularly too trusting, opening the door to strangers, etc. But of cours no one knew what Murdoch looked like. MF should have shown a photo or a drawing of this man to every member of her household. She endangered her family and friends by keeping things to herself, Yes I know she was traumatized by past events, but she's right in blaming herself